Economic and environmental concerns, i.e. improving efficiency and reducing emissions, are driving forces behind the ever increasing demand for higher gas turbine inlet temperatures. Designers of gas turbine engines recognize that a limitation to the efficiency and emissions of many gas turbine engines is the temperature capability of hot section components included in gas turbine inlets (examples include, but are not limited to blades, vanes, blade tracks, and combustor liners). Technology improvements in cooling, materials, and coatings are required to achieve higher inlet temperatures. As the temperature capability of Ni-based superalloys approach their intrinsic limit, further improvements in their temperature capability become increasingly difficult. Therefore, the emphasis in gas turbine materials development has shifted to thermal barrier coatings (TBC) and next generation high temperature materials, such as ceramic-based materials.
Ceramic matrix composites—sometimes referred to as CMCs are candidates to replace Ni-based superalloys for hot section structural components for next generation gas turbine engines. The key benefit to CMC engine components is their excellent high temperature mechanical, physical and chemical properties. This allows gas turbine engines to operate at much higher temperatures than the engines having metallic superalloy components. CMCs can provide the additional benefit of damage tolerance, which monolithic ceramics do not possess. That said, current two-dimensional (2D) preforming techniques for CMCs may limit shape complexity and impact mechanical performance by introducing material discontinuities.